The vestibular system is a portion of the inner ear which enables the sensation of angular and linear motion. Neural signals corresponding to this sensed motion are used by the brain to assist in a variety of processes including balance and determining orientation, and in related motor activities such as walking, standing, and visual orientation. The vestibular system includes the three semicircular canals and the otolithic organs. Various abnormalities of the vestibular system are known, and in severe cases they can result in significant disability for those so afflicted. In older persons, the loss of stability attendant upon vestibular dysfunction can lead to a greatly increased likelihood of a fall, and consequent loss of independence and mobility.
Ménière's disease is an abnormality of the vestibular system which affects approximately 1 in 2000 people worldwide. Ménière's has typical symptoms including periodic episodes of rotary vertigo or dizziness; fluctuating, progressive, unilateral or bilateral hearing loss; unilateral or bilateral tinnitus; and a sensation of fullness or pressure in one or both ears. It commonly begins with one symptom, and progresses to others. The symptoms of Ménière's are highly variable between patients, and it is relatively difficult to diagnose with certainty.
Approximately 85% of affected people can be treated with measures such as medication, dietary changes, lifestyle changes, or behavioral therapy. However, the remaining 15% are not assisted sufficiently by these measures, and typically turn to one of a variety of surgical procedures, all of which have significant downsides.
It has been proposed to provide a vestibular stimulator using electrical stimulation in order to treat vestibular disease. U.S. Pat. No. 6,314,324 discloses a vestibular stimulation device, using either electrodes placed externally, or implanted neural stimulation electrodes. U.S. Pat. No. 7,225,028 to Santina et al discloses a dual cochlear and vestibular stimulator.
It is an object of the present invention to provide an electrode array suitable for implantation within one or more semicircular canals of a user, so as to facilitate vestibular stimulation.